Far more complicated than simply feeling sad, this condition can also manifest itself physically.

The tricky thing with depression is that you might not be able to spot it right away. While the condition may commonly include telltale feelings of sadness or emptiness, there are numerous physical symptoms that can manifest as well, anything from fatigue to sleeping problems, unexplained aches and digestive issues.

The extensive range of symptoms may go toward explaining why so many who have depression find themselves diagnosed by a physician. Primary doctors treat roughly half of all behavioral health disorders in the U.S., according to the Patient-Centered Primary Care Collaborative.

“The spectrum of symptoms is quite wide and broad and it does take a good listener to sort it out versus a rapid prescription for a pain pill for chest pain or headaches that are due [to] depression or a sleeping pill for insomnia,” says Joel Temme, an internist at Alexandria Internal Medicine. “It takes very little time to write a prescription for a drug and it takes a long time to sit and listen carefully.”

Once physical conditions are ruled out and a diagnosis of depression is given, patients have several possible courses of treatment. In certain cases, physicians who feel comfortable doing so may write a prescription for anti-depressants, while others might recommend counseling or cognitive behavioral therapy first.

The National Institute of Mental Health estimates that in 2015 more than 16 million U.S. adults struggled with at least one major depressive episode over the prior year.

(Top Doctors 2018February 2018)